Laser Mégajoule (LMJ), a €3 billion research facility completed late last year near France's Atlantic coast, is a dead ringer for the world's leading laser fusion lab, the National Ignition Facility (NIF) in California. The similarities are no coincidence. Both sites were designed for the same purpose—to train scores of powerful laser beams on a single target, subjecting it, for an instant, to outlandish extremes of temperature and pressure. The two labs collaborated extensively and, like NIF's, LMJ's primary purpose is military: replicating nuclear explosions in miniature so that weapons scientists can ensure their bombs will detonate if needed without having to test them. The French facility, like its U.S. counterpart, will also pursue a sideline in inertial fusion energy research: crushing capsules of hydrogen isotopes with laser pulses so that the isotopes fuse into helium, releasing vast stores of energy that might one day be harnessed in a power plant. But some key design differences may give LMJ a better chance of achieving fusion energy than NIF has.
Editorial by Daniel Cleary on current state and history of nuclear fusion ignition facilities, with interviews of LMJ project leader Pierre Vivini (LMJ) and Plasma Physicist Dimitri Batani (Univ. of Bordeaux, CELIA).